Re: [PATCH 4/5] xfs: update metadata LSN in buffers during log recovery

On Thu, Aug 11, 2016 at 01:11:06PM -0400, Brian Foster wrote:
> @@ -2552,6 +2562,27 @@ xlog_recover_validate_buf_type(
>  		xfs_warn(mp, warnmsg);
>  		ASSERT(0);
>  	}
> +
> +	/*
> +	 * We must update the metadata LSN of the buffer as it is written out to
> +	 * ensure that older transactions never replay over this one and corrupt
> +	 * the buffer. This can occur if log recovery is interrupted at some
> +	 * point after the current transaction completes, at which point a
> +	 * subsequent mount starts recovery from the beginning.
> +	 *
> +	 * Write verifiers update the metadata LSN from log items attached to
> +	 * the buffer. Therefore, initialize a bli purely to carry the LSN to
> +	 * the verifier. We'll clean it up in our ->iodone() callback.
> +	 */
> +	if (bp->b_ops && current_lsn != NULLCOMMITLSN) {
> +		struct xfs_buf_log_item	*bip;
> +
> +		ASSERT(!bp->b_iodone || bp->b_iodone == xlog_recover_iodone);
> +		bp->b_iodone = xlog_recover_iodone;
> +		xfs_buf_item_init(bp, mp);
> +		bip = bp->b_fspriv;
> +		bip->bli_item.li_lsn = current_lsn;
> +	}
>  }

Of, so now we have two things we do when current_lsn !=
NULLCOMMITLSN. I'd change this to something like:


	ASSERT(bp->b_fspriv == NULL);
	if (current_lsn == NULLCOMMITLSN)
		return;

	if (warn) {
		....
	}

	if (!bp->b_ops)
		return

	/* add buf_item */

Cheers,

Dave.
-- 
Dave Chinner
[email protected]

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